I have two of them. I purchased a smaller one way back when they first started becoming a thing. We quickly learned it was too small for our family so we upgraded to a larger one. We now use them in tandem for family meals.
I'll give you a few examples. Especially in the summer months, I stock quick items like corndogs and chicken fingers in the freezer so the boys (ages 14 and 16) can quickly make their own lunch. The food comes out as it had been in the deep fryer or oven in less of half the time it would take to get the oven/oil warmed up and actually cook the food. If you have ever microwaved a corndog you know what a let down it is to not have that crunch when you bite in. The air fryer takes care of that and the food does seem much less oily. In fact, you can see how much oil was shed when you clean the tray.
We have tried all kinds of foods in the air fryers. Each unit is a little different so it may take a few tries to get the timing correct. Basically, anything that says frying is an option is a good candidate to try out. We've experimented with other foods that are traditionally baked like biscuits with some success as well. The outer crust has a crunch to it while the inside is fluffy. I've been using it to cook larger veggies like broccoli and asparagus as well. While you can cook stuff like hamburgers and chicken breasts, I caution you that it will make a mess in the tray so make sure you get a model that allows you to easily clean that tray under the basket. Both of ours are dishwasher safe but we normally just hand clean after each use.
Hope that helps. Let me know if you have any other questions or suggestions of things to try out.